At present, the union of lateral boxes for lifting structures for aircraft consists of a central metallic box that provides wings for inserting and riveting the lateral boxes. These in all cases have a flat structure, normally sloping upwards towards their free extremities.
Another known solution is a joint that incorporates upper or lower formers in titanium, with a central ribbing made of carbon fibre.
A third solution consists of a double shear joint.
This consists of upper and lower partial formers installed in the interior of the box, with exterior plates and central ribbing in composite material, creating a double shear joint.
Another known solution is a joint that includes a former in several sections.
In this case it consists of partial upper and lower formers installed from the outside of the box with a central ribbing in composite material.
Another solution incorporates formers in several places together with lattice ribbing. In this case it consists of partial upper and lower formers installed from the outside of the box with a central ribbing formed by bars in a latticed structure made from composite material.